US5532041A - Magnetic recording media and method for making them - Google Patents

Magnetic recording media and method for making them Download PDF

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Publication number
US5532041A
US5532041A US08/262,366 US26236694A US5532041A US 5532041 A US5532041 A US 5532041A US 26236694 A US26236694 A US 26236694A US 5532041 A US5532041 A US 5532041A
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United States
Prior art keywords
magnetic
magnetic layer
recording
coercivity
layer
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US08/262,366
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English (en)
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Yoshihiro Honjo
Yoshisuke Yamakawa
Hiroshi Kawahara
Eizo Tsunoda
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TDK Corp
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TDK Corp
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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/62—Record carriers characterised by the selection of the material
    • G11B5/68—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent
    • G11B5/70—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer
    • G11B5/716—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by two or more magnetic layers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S428/00—Stock material or miscellaneous articles
    • Y10S428/90—Magnetic feature
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
    • Y10T428/24355—Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/26—Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/26—Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
    • Y10T428/263—Coating layer not in excess of 5 mils thick or equivalent
    • Y10T428/264—Up to 3 mils
    • Y10T428/265—1 mil or less

Definitions

  • the present invention relates to a magnetic recording medium, esp., a magnetic recording medium used for recording video signals in direct recording systems by the low-range conversion of the chrominance signal components such as S-VHS format, and a method for making such a recording medium.
  • a video signal comprises a chrominance signal component and a luminance signal component.
  • Applied to the domestic VCR standards for VHS, etc. are direct recording systems by the low-range conversion of the chrominance signals in which they are converted into low frequency.
  • a coated type of video tape used for such home VCRs has been increasingly advanced in performance by the micronization of magnetic powders and improvements in the surface properties of a magnetic layer.
  • the micronization of magnetic powders and the improvements in the surface properties of magnetic layers increase high-range output and reduce noise, improving the luminance signal S/N.
  • the improvements in the surface properties of a magnetic layer also serve to improve the chrominance signal S/N.
  • the recording frequency of the luminance signal preset is so high that its characteristics can be improved increasingly.
  • the magnetic powders are further micronized to achieve much more increased coercivity than before.
  • the S-VHS format makes a much larger difference in the recording frequency between the luminance and chrominance signals, since it is substantially similar to the VHS format in the recording frequency of the chrominance signal.
  • the present invention accomplished with such situations in mind, has for its object to provide a magnetic recording medium excelling in both the luminance signal S/N and the chrominance S/N and improved in durability, and a method for making it.
  • a magnetic recording medium for recording two or more signals having different frequency bands by frequency multiplex recording, characterized in that a non-magnetic substrate has on it a first magnetic layer and a second magnetic layer in that order,
  • said second magnetic layer having a thickness amounting to 70% or less of the shortest recording wavelength of the signals to be recorded.
  • a magnetic recording medium as recited in the 1st aspect, which is used to record a video signal comprising a luminance signal and a chrominance signal in a direct recording system by the low-range conversion of the chrominance signal component.
  • a magnetic recording medium as recited in the 1st aspect, wherein the second magnetic layer has a thickness of 0.2 ⁇ m or more.
  • a magnetic recording medium as set forth in the 1st aspect, wherein the second magnetic layer is higher in coercivity than the first magnetic layer.
  • a magnetic recording medium as set forth in the 1st aspect, wherein the second magnetic layer has a centerline average surface roughness --Ra--of 0.01 ⁇ m or lower.
  • a magnetic recording medium as set forth in the 6th aspect, wherein the non-magnetic substrate has a centerline average surface roughness --Ra--of 0.01 ⁇ m or lower.
  • the non-magnetic substrate is coated thereon with a magnetic coating material for the first magnetic layer, followed by smoothing and drying, and
  • Another coating material for the second magnetic layer is then provided on the first magnetic layer by coating.
  • the magnetic recording medium of the present invention includes on a non-magnetic substrate first and second magnetic layers on that order, said second magnetic layer having a thickness amounting to 70% or lower of the shortest recording wavelength of the signals to be recorded. This thickness is virtually equal to the effective recording depth of the luminance signal.
  • the magnetic characteristics of the second and first magnetic layers are suitable for recording the luminance and chrominance signals, respectively.
  • the luminance signal S/N is improved, because it is substantially recorded on the second magnetic layer alone.
  • the thickness of the second magnetic layer is virtually equal to only the effective recording depth of the luminance signal, it is possible to minimize the proportion of the chrominance signal to be recorded on the second magnetic layer, while attaining the best luminance signal S/N.
  • the proportion of the chrominance signal to be recorded on the first magnetic layer can be increased to a maximum so that the chrominance signal S/N ratio can be improved very satisfactorily.
  • the magnetic layer arrangement of a double-layer structure according to the present invention has improved mechanical strength and durability than a single magnetic layer of similar thickness.
  • This mechanical strength can be further improved by coating the coating material for the second magnetic layer on the first magnetic layer after the latter has been dried and, preferably, cured.
  • FIG. 1 is a graph illustrating the relation between the coercivity of a magnetic layer and the playback output of a luminance signal
  • FIG. 2 is a graph illustrating the relation between the coercivity of a magnetic layer and the playback output of a chrominance signal
  • FIG. 3 is a graph illustrating the relation between the thickness of a magnetic layer and the playback output of a luminance signal
  • FIG. 4 is a graph illustrating the relation between the thickness of a magnetic layer and the playback outputs of chrominance and luminance signals.
  • the magnetic recording medium of the present invention is used with systems of recording two or more signals having different frequency bands by frequency multiplex recording.
  • the video signal comprises a luminance signal component and a chrominance signal component, with the chrominance signal zone lying in a region of frequency lower than does the luminance signal zone.
  • the magnetic recording medium of the present invention includes on the non-magnetic substrate the first and second magnetic layers on that order, said second recording layer having a thickness amounting to 70% or less of the shortest recording wavelength of the signals to be recorded.
  • the "shortest recording wavelength” refers to a white peak wavelength of the luminance signal component. In such saturation recording as occurs with the luminance signal, the above thickness is nearly in coincidence with the effective recording depth.
  • the proportion of the chrominance signal to be recorded on the first magnetic layer is so reduced that its output and S/N drop.
  • the chrominance signal output and S/N are improved strikingly.
  • the second magnetic layer should preferably be 0.2 ⁇ m or upwards in thickness.
  • the thickness of the second magnetic layer is less than that lower limit, it is substantially impossible to record the luminance signal in the second magnetic layer alone, resulting in drops of its output and S/N.
  • abrasive particles, etc. contained in it would be exposed to view at a thickness less than the above lower limit.
  • the thickness of the first magnetic layer is not critical, and may be determined such that the total thickness of the first and second magnetic layers assumes an appropriate value depending upon various systems to which the magnetic recording medium is applied.
  • Table 1 Set out in Table 1 are the thickness range of the second magnetic layer and the preferable range of the total thickness of the first and second magnetic layers in various video recording systems.
  • each magnetic layer may be found from a transmission type electron microphotograph--TEM photograph--of the section of the magnetic recording medium.
  • the second magnetic layer is higher in coercivity than the first magnetic layer.
  • the luminance signal is substantially recorded on the second magnetic layer alone, successful recording of the luminance signal of a short wavelength can be achieved by allowing the second magnetic layer to have higher coercivity. It is then possible to make successful recording of the chrominance signal, which is of a wavelength so long that it cannot be subject to saturation recording, on the first magnetic layer having lower coercivity.
  • first and second magnetic layers may lie in such ranges as lending themselves well to recording the chrominance and luminance signals.
  • the remanence and squareness ratio may preferably lie within such ranges as set out in Table 2.
  • the center-line average surface roughness--Ra--of the second magnetic layer In order to make successful recording of signals of a short wavelength, however, it should preferably be 0.01 ⁇ m or below. The lower limit should then preferably be about 0.002 ⁇ m, because no sufficient traveling performance can be achieved when the layer is made smooth excessively on its surface.
  • Ra is provided for in JIS B 0601.
  • the Ra of the non-magnetic substrate is 0.01 ⁇ m or below.
  • the lower limit is then about 0.002 ⁇ m due to the need of ensuring improved traveling performance in the steps of producing substrates and media.
  • the Ra of the first magnetic layer should preferably 0.01 ⁇ m or below.
  • the lower limit should then preferably be 0.002 ⁇ m, because of the surface properties of the first magnetic layer being almost faithfully reflected in those of the second magnetic layer and for the same reason as set forth in connection with the lower limit of the Ra of the second magnetic layer.
  • the preferable ranges set out in Tables 1 and 2 follow the NTSC standards.
  • the preferable thickness of the second magnetic layer may similarly be found according to other standards inclusive of the PAL standards.
  • Preferable ranges of other conditions may be found experimentally or in the manner provided for in the NTSC standards.
  • first and second magnetic layers have such properties as stated above, no particular limitation is imposed thereon.
  • various coated types of magnetic layers heretofore known in the art may be used.
  • magnetic layers formed of magnetic particles and binders may be used to which various additives such as electrically conductive fillers, abrasives, solid lubricants, liquid lubricants and surfactants may be added, if required.
  • additives such as electrically conductive fillers, abrasives, solid lubricants, liquid lubricants and surfactants may be added, if required.
  • magnétique particles use may be made of any material which can be used for ordinary magnetic recording media.
  • suitable particles such as iron oxide particles, e.g., ⁇ --Fe 2 O 3 ; Co-containing iron oxide particles, e.g., Co-containing ⁇ --Fe 2 O 3 ; magnetic metal particles; barium ferrite particles; and CrO 2 particles may be selected depending upon the purpose.
  • Their coercivity and specific surface area may also be determined depending upon the purpose.
  • the coated type of magnetic layer may have a particle size suitable for the frequency to be recorded on each of its layer parts, i.e., the first and second magnetic layer parts.
  • a particle size suitable for the frequency to be recorded on each of its layer parts i.e., the first and second magnetic layer parts.
  • magnetic powders of a smaller BET value are used for the first magnetic layer, whereas magnetic powders of a larger BET value are employed for the second magnetic layer.
  • magnetic metal powders or Co-containing iron oxide particles having a BET value of about 30 to 45 m 2 /g and magnetic metal powders having a BET value of about 50 to 65 m 2 /g be used for the first and second magnetic layers, respectively.
  • binder use may be made of any material which can be used for ordinary magnetic recording media.
  • suitable binders such as reactive types of binders such as heat-curing and reactive resins; and radiation curing types of binders such as radiation curing resins may be selected depending upon the purpose.
  • a material chosen from various flexible materials and various rigid materials depending upon the purpose may be formed into a predetermined tape or other shape of predetermined size.
  • polyesters such as polyethylene terephthalate may be used as the flexible materials.
  • a back coat may optionally be provided on the other side of the non-magnetic substrate, i.e., the side in opposition to the side having the magnetic layers.
  • the back coat is not critical, and may be any known coated type of back coat containing electrically conductive fillers and various pigments, or alternatively formed of a plasma-polymerized film.
  • such a magnetic recording medium is produced by coating a coating material for the first magnetic layer on the non-magnetic substrate, followed by at least drying and smoothing, and providing another coating material for the second magnetic layer on the first magnetic layer.
  • the coating material for the second magnetic layer is provided on the first magnetic layer by coating after the coating material for the first magnetic layer has been cured.
  • the preferred degree of drying of the coating material for the first magnetic layer at the time of providing the coating material for the second magnetic layer by coating may be expressed in terms of the percentage of residual solvents. This percentage is preferably 1% by weight or below.
  • the preferable degree of curing of the coating material for the first magnetic layer may also be expressed in terms of gel fraction.
  • this fraction is upward of 70%.
  • the gel fraction refers to the weight ratio of the binder before and after the coated film is immersed in an organic solvent such as methyl ethyl ketone, by way of example.
  • the immersion conditions for example, are about 2 hours at 80° C.
  • the coating material for the first magnetic layer has preferably an Ra lying within such a range as defined above. This Ra is preserved even after curing.
  • the luminance and chrominance signals are both recorded on the second magnetic layer.
  • the chrominance signals which are substantially recorded on the first magnetic layer.
  • sound carrier signals may be recorded on both the first and second magnetic layers.
  • not only linear sound carrier signal but also hi-fi sound carrier signal are recorded in the so-called baseband recording manner in which the audio signal is recorded down to the depths of the magnetic layer of video tape, wherein the video signal is recorded on the surface of the magnetic layer of video tape.
  • the video signal is superimposed at different azimuth angles on the hi-fi sound carrier signal already recorded.
  • a part of the hi-fi sound carrier signal is erased.
  • the coercivity of the second magnetic layer is made higher than that of the first magnetic layer in the present invention, it is substantially unlikely that the hi-fi sound carrier signal recorded on the second magnetic layer may be erased by the superimposed recording of the video signal. This results in an improvement in the hi-fi sound carrier signal output. It is noted, however, that no simultaneous reproduction of the hi-fi sound carrier and video signals occurs, because they are recorded at different azimuth angles.
  • the magnetic layer of lower coercivity is suitable for recording a sound carrier signal of low frequency
  • the hi-fi sound recording signal output is further improved with an improvement in the linear sound carrier signal output.
  • the magnetic recording medium of the present invention is very effective for recording video signals in the direct recording system by the low-range conversion of the chrominance signals and are suitable for home video tapes for the S-VHS, VHS, ⁇ , high-band ⁇ , super high-band ⁇ , ED- ⁇ , 8-mm and Hi8 formats.
  • the present invention is most advantageously applicable to the coated type of video tape for the S-VHS format in which there is a large difference in the recording wavelength between the luminance and chrominance signals.
  • the present invention is effective for not only recording the luminance and chrominance signals separately but also recording two or more signals having different recording frequency bands.
  • Such recording systems include the above-mentioned combination of video signals with hi-fi sound carrier signals, a combination of video signals with PCM sound carrier signals or tracking servo signals, and the like.
  • the present invention is applicable to not only video tapes but also video floppy disks for still video cameras.
  • a magnetic layer arrangement of a multi-layered structure may be provided corresponding to the effective recording depth of each signal component.
  • tape samples were prepared in the following manners.
  • compositions containing magnetic powders having different coercivities were put in a ball mill, in which they were dispersed for 24 hours to prepare various magnetic coating materials.
  • Composition I mentioned below, was used to form a magnetic layer having a coercivity of 1200 Oe or below, while Composition II, again mentioned below, was used to form a magnetic layer having a coercivity exceeding 1200 Oe.
  • the obtained magnetic coating materials were coated on a 14- ⁇ m thick polyester base film, followed by drying and surface smoothing. Afterwards, they were subjected to 24-hour curing reactions at 60° C.
  • the film was cut to a width of 12.65 mm to obtain magnetic tape samples.
  • the luminance and chrominance signal outputs were measured in the following manners.
  • NV-FS made by Matsushita, modified such that it could work in a still state
  • HP3325A and HP3585A both made by Yokogawa-Hewlett-Packard, Ltd.
  • a 7-MHz sine wave was recorded on each sample with a recording current providing a maximum output, and the playback output was read out on the spectrum analyzer.
  • the 629-kHz signal was superimposed and recorded on the 7-MHz signal with the thus found optimum recording current.
  • the chrominance signal output was then determined by the 629-kHz component of the playback output components.
  • FIGS. 1 and 2 The relations between the coercivity (Hc) of each magnetic layer and the luminance (Y) and chrominance (C) signal playback outputs are graphically illustrated in FIGS. 1 and 2, respectively.
  • the results of measurement on magnetic metal and ferrite heads are also shown in FIG. 1.
  • the results of measurement on the magnetic metal head are illustrated in FIG. 2.
  • the effective recording depth of the luminance signal in the S-VHS format was measured.
  • a coating material obtained from this composition in similar manners as stated above, was coated a polyester base film at varied thickness by means of a reverse roll. After drying and surface smoothing, the resultant coat was cured and the film was cut in similar manners as stated above, thereby obtaining tape samples including magnetic layers varying in thickness.
  • the thickness of the base film was selected from a range of 14 to 17 ⁇ m such that the total tape thickness of each sample was substantially kept constant.
  • FIG. 4 also illustrates the playback output of the chrominance signal recorded with the optimum recording current as found above and the chrominance signal playback output when saturation recording was carried out, together with the luminance signal playback output shown in FIG. 3.
  • Prepared was an S-VHS tape sample including the first and second magnetic layers.
  • composition III The same as Composition III.
  • a coating material prepared from Composition IV was coated on a polyester base film by means of a reverse roll, followed by drying and smoothing. Afterwards, the film was placed in a constant temperature chamber of 60° C. for 24-hour curing, thereby obtaining the first magnetic layer.
  • the magnetic coating material was found to have a percentage of residual solvents of 0.5% by weight and a degree of curing of 85% expressed in terms of gel fraction.
  • the gel fraction was found by measuring the weight ratio of the binder before and after immersing the magnetic layer in methyl ethyl ketone at 80° C. for 2 hours.
  • a magnetic coating material prepared from Composition V was coated on the first magnetic layer by means of a reverse roll, followed by drying and surface smoothing.
  • the base film was coated on its back side with a coating material comprising the following Composition VI at a thickness of about 1.0 ⁇ m, followed by drying.
  • the base film was cut to a width of 12.65 mm to obtain a tape sample.
  • the base film had an Ra regulated to 0.0070 ⁇ m.
  • the VTR used for measurement was a BR-S711 made by JVC, and the signal oscillator and spectrum analyzer used a TG-7 made by Hewlett Packard Shibasoku and an HP3585A made by respectively.
  • the playback output was determined by measuring the output of each carrier frequency component with the use of the spectrum analyzer, and the S/N was measured with the use of a 925D made by Shibasoku.
  • the still life referred to in Table 4 was estimated with an HR-D380 made by JVC modified such that it could be kept still unrestrictedly. Recording and reproducing color bars were continued until the still picture was severely disordered. By the length of this time, the still life was evaluated.
  • Sample Nos. 2-5 in which the second magnetic layer had a thickness lying within the range of the present invention, all give high luminance and chrominance signal outputs with improvements in their S/N.
  • Sample Nos. 6-8 in which the second magnetic layer had a thickness larger than the effective recording depth of the luminance signal, are much reduced in the chrominance signal outputs and S/N. Furthermore, Sample No. 1 having the first magnetic layer alone is so unbalanced in its frequency characteristics that its S/N drops.
  • a video tape sample for the 8-mm format was prepared, which included a magnetic layer arrangement of a coated type of double-layer structure.
  • the first magnetic layer part had a coercivity of 700 Oe and a remanence of 1800 G, while the second magnetic layer part had a coercivity of 1550 Oe and a remanence of 2700 G.
  • the samples were tested at varied thickness of the 1st and 2nd magnetic layers for the playback output and S/N of each signal as well as their still life. Prepared for the purpose of comparison were also samples each having the first or second magnetic layer alone, which were in turn tested for similar characteristics.
  • the present invention achieves magnetic recording media which can successfully record both the luminance and chrominance signals and are of improved durability.

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  • Magnetic Record Carriers (AREA)
  • Paints Or Removers (AREA)
  • Recording Or Reproducing By Magnetic Means (AREA)
  • Manufacturing Of Magnetic Record Carriers (AREA)
US08/262,366 1989-07-18 1994-06-20 Magnetic recording media and method for making them Expired - Lifetime US5532041A (en)

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JP1185345A JPH0349030A (ja) 1989-07-18 1989-07-18 磁気記録媒体およびその製造方法
JP1-185345 1989-07-18
US55364190A 1990-07-18 1990-07-18
US96845192A 1992-10-29 1992-10-29
US08/262,366 US5532041A (en) 1989-07-18 1994-06-20 Magnetic recording media and method for making them

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EP (1) EP0409216B1 (fr)
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US5756148A (en) * 1991-01-21 1998-05-26 Fuji Photo Film Co., Ltd. Magnetic recording medium
US5827600A (en) * 1991-01-21 1998-10-27 Fuji Photo Film Co., Ltd. Magnetic recording medium
US6096406A (en) * 1997-07-15 2000-08-01 Fuji Photo Film Co., Ltd. Magnetic recording medium
US6203934B1 (en) 1997-10-14 2001-03-20 Fui Photo Film Co., Ltd. Magnetic recording medium
US6254964B1 (en) 1997-02-10 2001-07-03 Fuji Photo Film Co., Ltd. Magnetic recording medium
US6291052B1 (en) 1997-06-30 2001-09-18 Fuji Photo Film Co., Ltd. Magnetic recording medium
US6316077B1 (en) 1998-06-22 2001-11-13 Fuji Photo Film Co., Ltd. Magnetic recording medium
US6432503B2 (en) 1997-03-31 2002-08-13 Fuji Photo Film Co., Ltd. Magnetic recording medium
US6444290B1 (en) 1998-06-11 2002-09-03 Fuji Photo Film Co., Ltd. Magnetic recording medium comprising a support containing a specific size filler and having a specific concentration of surface protrusions
US6579592B1 (en) 1996-11-29 2003-06-17 Fuji Photo Film Co., Ltd Magnetic recording tape with controlled Hc and magnetic flux/unit area value and controlled Cl/Fe intensity
US20080003378A1 (en) * 2006-06-30 2008-01-03 Imation Corp. Fluid jet printing recording media layers
US11410697B2 (en) * 2019-08-20 2022-08-09 International Business Machines Corporation Process for forming underlayer for tape media
US11749306B2 (en) 2019-08-20 2023-09-05 International Business Machines Corporation Tape media having synergistic magnetic recording layer and underlayer
US11790942B2 (en) 2019-08-20 2023-10-17 International Business Machines Corporation Process for forming magnetic recording layer for tape media
US12014760B2 (en) 2019-08-20 2024-06-18 International Business Machines Corporation Process for forming tape media having synergistic magnetic recording layer and underlayer

Families Citing this family (4)

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Publication number Priority date Publication date Assignee Title
JP3023683B2 (ja) * 1989-08-29 2000-03-21 コニカ株式会社 磁気記録媒体の製造方法
JP2744114B2 (ja) * 1990-05-11 1998-04-28 株式会社東芝 多周波重畳磁気記録方式および多周波重畳磁気ヘッド記録用磁気記録媒体
DE69213115T3 (de) † 1991-04-25 2005-05-19 Fuji Photo Film Co., Ltd., Minami-Ashigara Magnetische Aufzeichnungsträger
JPH064850A (ja) * 1992-06-22 1994-01-14 Sony Corp 磁気記録媒体及び磁気記録方法

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US11410697B2 (en) * 2019-08-20 2022-08-09 International Business Machines Corporation Process for forming underlayer for tape media
US11749306B2 (en) 2019-08-20 2023-09-05 International Business Machines Corporation Tape media having synergistic magnetic recording layer and underlayer
US11790942B2 (en) 2019-08-20 2023-10-17 International Business Machines Corporation Process for forming magnetic recording layer for tape media
US12014760B2 (en) 2019-08-20 2024-06-18 International Business Machines Corporation Process for forming tape media having synergistic magnetic recording layer and underlayer
US12567442B2 (en) 2019-08-20 2026-03-03 International Business Machines Corporation Process for forming underlayer for tape media

Also Published As

Publication number Publication date
EP0409216B1 (fr) 1996-04-03
JPH0349030A (ja) 1991-03-01
DE69026315D1 (de) 1996-05-09
EP0409216A3 (en) 1991-04-10
DE69026315T2 (de) 1996-12-05
EP0409216A2 (fr) 1991-01-23

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